


The Equation for Glory

by CourierNinetyTwo



Series: Modern Magic AU [3]
Category: Fire Emblem Series, Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Alternate Universe - Modern with Magic, F/F
Language: English
Status: Completed
Published: 2020-05-30
Updated: 2020-05-30
Packaged: 2021-03-03 04:08:12
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,286
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24458707
Author URL: https://archiveofourown.org/users/CourierNinetyTwo/pseuds/CourierNinetyTwo
Summary: Hilda discovers a solution to Edelgard and Lysithea's sacrificial magic, but at what cost?
Relationships: Hilda Valentine Goneril/Edelgard von Hresvelg/Lysithea von Ordelia
Series: Modern Magic AU [3]
Series URL: https://archiveofourown.org/series/1718044
Comments: 3
Kudos: 59





	The Equation for Glory

**Author's Note:**

> For birdhymns!

There were a lot of advantages to having two girlfriends, but Lysithea's favorite aspect had to be waking up between them.

The bed in her dorm was huge—she spent a good deal of time in it, and needed room for magic and homework simultaneously—which meant that soon after she and Edelgard got together, the older girl was sleeping there too, back to the wall and an arm around her stomach. Once the two of them figured out that they were both really into Hilda and the feeling was mutual, Hilda slept there facing her, offering a warm and comforting weight.

So when Lysithea's eyes fluttered open and the pillow beside her was empty, it was a surprise. She blinked past the shadows of the room, trying to make sense of the shapes and various pinpoints of light. First were the stars outside the window, so it was still late. Second was her nest of chargers near the desk, its little red constellation slowly blossoming to specks of green. Last was the bright square of Hilda's phone, tilted diagonally towards the desk as Hilda herself wrote notes in a quiet, sustained frenzy.

Lysithea's first instinct was to sit up and ask what was going on, but Edelgard was silent and still behind her, and such peaceful nights were hard to come by. She decided to watch instead, piecing together what Hilda was working on as her eyes adjusted to the darkness. A thick book was by her elbow, and Lystithea pieced out the title in Greek: _Ἱερὸς Λόχος_. She didn't know it, but Hilda kept flipping from page to page, making notes both on her paper and the text itself.

"Yes," Hilda whispered under her breath, both hands clenched into fists. The taller girl looked like she'd just been shocked full of energy, but was doing everything she could not to burst with her girlfriends sleeping in the same room. " _Yes_."

It was very sweet.

Now Lysithea was too curious not to ask. "Is everything okay, Hilda? It's two in the morning."

"Shit!" Hilda jumped in her chair, then awkwardly spun to face Lysithea. "Sorry, I was really trying not to wake you up. Is Edelgard—"

"Am I what?" Edelgard muttered, her arm tightening around Lysithea. "Awake? Yes."

Well, no pouring that one back into the cauldron. "Sorry, El. I didn't want to wake you up either."

"It's all right." She sat up behind Lysithea, wiry limbs covered in scars as she stretched and brushed sleep-strewn strands of white hair back from her face. "What's all the excitement about?"

"I found the answer." Hilda held up her notebook in both hands, her smile bright enough to light up the whole room. Even half-asleep, Lysithea knew the alchemical symbols covering the page like the back of her own hand, but couldn't piece together their configuration. "Only had to go back about twenty-five hundred years. You know, a little light reading."

Lysithea sat up too, determined to shake herself awake the rest of the way. "The answer to what?"

"To you. To Edelgard." Excitement bubbled over Hilda's words, and she cleared her throat, shoulders straightening. "I mean, to your Crests. The magic eating at you whenever you cast a spell. I can fix it."

Shock dispelled Lysithea's fatigue in a blink. "What? How?"

"So, a couple millennia ago, there was this group of soldiers: the Sacred Band of Thebes. A bunch of Greek guys who were dating, which you know, cool—but not really the point. Or not the whole point anyway." Hilda sucked in a quick breath between her teeth to keep talking. "They were considered invincible for decades against untold odds. But it wasn't just the power of love backing that up."

"One would think not," Edelgard said, raising a brow.

"It was _alchemy_ ," Hilda added swiftly, "inscribed on each couple as they took an oath. They weren't actually invincible, but they shared a pool of power. They could draw on each other's strength, over and over again. Their enemies didn't stand a chance, because they'd always buckle first."

Lysithea frowned. "Hilda, Edelgard and I can't do that to each other. Our magic has the same problem—we'd eat one another alive."

It was then that Hilda looked nervous, which was so out of character that Lysithea wondered if she was actually lost in an unusually hopeful dream. 

"That won't happen if I'm in the equation too," Hilda said softly. "I have all the soul you need to spare. My Crest doesn't have that cost."

"But we'd both be taking from you at once." Edelgard's voice was sharp with concern. "That has to have a price."

Hilda shrugged, jostling the edge of her pink ponytail back over one shoulder. "El, I'm happy to take more naps if that means you _live longer_."

"Wait, I know what this is." Lysithea couldn't believe she hadn't put it together before. Was it really so simple? "It's the Equation for Glory, which is way older than the Greeks. Gilgamesh tried to use it with Enkidu and failed."

"Yeah, which totally sucks." Hilda smiled sheepishly. "Turns out everyone involved has to have magic for it to stick, but all of us do. There's no reason it won't work."

Lysithea wasn't sure what to say. Relief washed over her like a wave, but like a wave it overwhelmed everything else, and the hot trails dripping down her face were sudden, unstoppable tears.

It was Edelgard that broke the silence. All reproach in her voice was gone, replaced by something close to fear. "Hilda, of course it will work, but it's...it's forever. Soul bonds don't break, even if someone dies."

In a flash, Hilda was out of her chair with one knee against the bed. Tender, calloused fingers cupped Lysithea's cheek, Hilda's other hand framing Edelgard's jaw with the same deliberate care.

"You think I wouldn't give you forever?" Hilda asked, voice fierce with passion. "Both of you? Eternity's the least you deserve, after how much the world's taken away."

Lysithea choked back a sob, and leaned forward, offering Hilda a kiss because the words simply wouldn't come. It was a mess of breath, salt and heat, but she only pulled away so Edelgard could take her place. She kept a hand linked over Hilda's, the other resting on Edelgard's knee so the line of contact between them was never broken.

"I'm going to have to fix my makeup before I draw the circle," Hilda sniffled, eyeliner painting her face in dark tracks. "Love you."

"I love you too," Lysithea whispered, echoed in the same breath with Edelgard. "Both of you."

"You're brilliant," Edelgard added, turning to kiss Hilda's fingers, smeared with ink after hours of work. "But let's wait until the morning."

Hilda sputtered in surprise. "Hey, I don't want you losing any more time than you already have—"

"I'm not going to cast any spells in the next six hours," Edelgard gently countered. "Let's make a date out of it. A full night's sleep, getting breakfast together..."

Lysithea caught on immediately, smiling wide. "We can go shopping too. Get a nice new outfit for the occasion. Then when it gets late..."

"You two are making an exhausting alchemical ritual sound way hotter than it should," Hilda muttered, face pink.

"That's the best part." With her tone light and teasing, Lysithea pressed another tender kiss to Hilda's brow. "Afterwards, we'll be tired and can go right to bed."

"Sound like a deal?" Edelgard asked.

"Deal." Hilda wrapped them both in a tight hug, her open delight giving her even more strength than usual. Lysithea fondly wheezed. "Some things really do come full circle, huh?"

By some mercy, they did indeed.

—


End file.
